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Word ProBLEMS. You Don’t Have to be Afraid…. WORD PROBLEMS. Look for KEYWORDS. Draw a PICTURE or VISUALIZE. Create a PLAN. ESTIMATE and think about your UNITS. SOLVE for the answer. Example.
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Word ProBLEMS You Don’t Have to be Afraid….
WORD PROBLEMS • Look for KEYWORDS. • Draw a PICTURE or VISUALIZE. • Create a PLAN. • ESTIMATE and think about your UNITS. • SOLVE for the answer.
Example As you go through the presentation, work through the strategies to solve the following word problem: Mrs. London fenced in her yard a year ago but the fence is already falling down. The new (more reliable) handyman is going to charge her $5 per foot of fencing. Last year, Mrs. London spent $1020 altogether to fence the perimeter of her yard. Her yard is 70 feet by 30 feet minus a 4-foot entrance, plus she tipped the person $20 last year. How much did she pay per foot last year? Is she being charged more than last year?
Identify Keywords Mrs. London fenced in her front yard a year ago. This year she is going to fence in her backyard. The new handyman is going to charge her $5 per foot of fencing. Last year, Mrs. London spent $1020 altogether to fence the perimeter of her yard. Her backyard is 70 feet by 30 feet minus a 4-foot entrance, plus she tipped the person $20. How much did she pay per foot last year? Is she being charged more than last year? Keywords Per- indicates multiplication Altogether - indicates addition Perimeter - indicates we will have to find the total distance around, indicates addition Minus – indicates subtraction Plus – indicates addition
Draw a Picture • Represent the words using pictures. Draw: • a picture for every object • a circle or bar to represent fractions • a number line
Draw a Picture 70 feet 30 feet 30 feet 4 feet
Create a Plan • Decide: • how many steps you need • operations • Then, test with numbers to see if it will produce the predicted answer.
Create a Plan 1) Find perimeter. Perimeter = 70 + 70 + 30+ 30 - 4 = 196 feet 2) Find the unknown. The question asks about price per foot. So the unknown will be the price per foot. Let x= price per foot. 3) Write an equation. See next slide 4) Estimate an answer. 196x + 20 = 1020, you can estimate the answer with 200x = 1000. So you should expect the answer to be about 5. 5) Solve and compare to estimate. NO SPOILERS! Keep reading!
Create a Plan 70 feet 30 feet THINK: If fencing costs $2 per foot then, the cost for this side would be $30*2. In general, the cost is the length * price per foot. 30 feet 4 feet Price per foot = x Perimeter = 196 feet Total cost = 1020 196x = cost of fencing 20 = tip 196x + 20 = total cost 196x + 20 = 1020 so……
Think about Units • Does the answer seem reasonable? Ask yourself the following questions: • What type of quantity was mentioned in the question? • What were my original units? • Can my answer be negative? • Can my answer be a decimal or fraction? (People can’t be fractional!) • Which quadrant should my answer be in? • Can my answer be that large/small given what I started with? • Can my answer be that large/small given what I know about the world?
Think about Units • The question asks you to find price per foot. • The units for your answer will be dollars per foot ($/foot) • Dollars cannot be negative in this case. • The answer should have two decimal place values. • The answer should be close to our estimate of $5/foot.
Solve for the Answer 196x + 20 = 1020 -20 -20 196x = 1000 196x = 1000 196 196 x = $5.10 Mrs. London paid $5.10 per foot of fencing last year. She is paying slightly less than last year! Note that we had to round our answer to $5.10. The answer made sense given our estimate.
Another Example A remote control car moves 1.5 feet every second. If the car starts 2 feet away from me, how long before it is in the next room (10 feet away)? 1 2 3 4 5 6 7 8 9 10 0 1 sec. 2 sec. 3 sec. After 3 seconds, 1.5 + 1.5 + 1.5 = 3(1.5) or s(1.5) So….. 2 + 1.5s= 10 and solve to get ~5.3 seconds